it could even be released for free to ensure users upgrade. From there, the idea is that Microsoft would offer regular yearly updates which will be standardized across desktop and mobile devices.Apparently, the word is that Windows Blue will look much like Windows 8 with just some minor UI tweaks, and will likely keep the Windows 8 name, but everything behind it could be very different, including the pricing. Microsoft wants Windows Blue to be on everyone's computer, which means
Microsoft is also planning to release a new Windows SDK along with the updates, and will stop accepting apps written using the Windows 8 SDK, although Windows 8 legacy apps will still run on Windows Blue. This change in the SDK could easily include options to make apps universal and run on any Windows device from phones to tablets and desktops.
None of that sounds too far fetched, and it all seems like things Microsoft has been working towards. The strange thing is that the reports have Microsoft releasing this update in mid-2013,. It's unclear if you'll have to be coming from Windows 8 to update to Blue, but given that Microsoft wants this to be the standard, it would seem likely that you could come from older versions of Windows. Even if the upgrade is free initially, it will likely look like a yearly fee or subscription to keep the updates coming.
source: The Verge